Gypsum As an Agricultural Amendment

Bulletin 945 Authors

Liming Chen Research Associate School of Environment and Natural Resources The Ohio State University

Warren A. Dick Professor School of Environment and Natural Resources The Ohio State University

Disclaimer This guide was funded in part by the U.S. Environmental Protection Agency (U.S. EPA) under a Resource Conservation Challenge grant. The contents of this guide do not necessarily reflect the views or policies of the U.S. EPA. The mention of trade names, individual companies, commercial products, or inclusion of web links to sites describing such materials or services is provided for information exchange and educational purposes only. Such mention does not constitute an endorsement, recommendation for use, or any form of implied warranty.

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Preface ...... 4 Chapter 1: Sources and Properties of Gypsum ...... 5 Chapter 2: Properties of Gypsum That Provide Benefits for Agricultural Uses ...... 8 Chapter 3: Agricultural and Land Application Uses of Gypsum ...... 13 Chapter 4: Gypsum Application ...... 18 Chapter 5: Economic Considerations Related to Gypsum Use ...... 24 Chapter 6: Analytical and Technical Support ...... 27 Chapter 7: Gypsum Handling and Storage ...... 30 List of Figures ...... 33 List of Tables ...... 34 Abbreviations and Basic Conversion Factors ...... 34 Element Symbols ...... 34 Conversion Factors for SI and Non-SI Units ...... 35

Gypsum as an Agricultural Amendment: General Use Guidelines 3 Preface Gypsum is one of the earliest forms of fertilizer used A sustainable society cannot continue to extract in the United States. It has been applied to agricultural resources to create products and/or by-products that soils for more than 250 years. Gypsum is a moderately are then subsequently disposed of in landfills. It is soluble source of the essential plant nutrients, calcium imperative that recycling of all kinds of materials is and sulfur, and can improve overall plant growth. encouraged and becomes more common. Agricultural Gypsum amendments can also improve the physical applications represent important new beneficial uses and chemical properties of soils, thus reducing erosion for FGD gypsum. It can augment or replace commer- losses of soils and nutrient concentrations (especially cial mined gypsum, thus avoiding both energy-inten- phosphorus) in surface water runoff. Gypsum is the sive and water-intensive mining activities associated most commonly used amendment for sodic soil recla- with gypsum extraction. mation and can be included as a component in Currently there is a lack of published guidelines that synthetic soils used in nursery, greenhouse, and land- provide general best management practices related to scape applications. These multiple uses of gypsum land application uses of gypsum, including FGD represent potential benefits to agricultural and horti- gypsum. To overcome this lack of information, Region cultural users. 5 of the U.S. Environmental Protection Agency and Currently, a large amount of flue gas desulfurization The Ohio State University provided support to the (FGD) gypsum is produced by removal of sulfur authors to prepare this management guide titled dioxide (SO₂) from flue gas streams when energy Gypsum as an Agricultural Amendment: General Use sources, generally coal, containing high concentrations Guidelines. An abundance of practical information of sulfur (S) are burned. Initially, most of the FGD related to agricultural and land application uses of gypsum produced in the United States was used in the FGD gypsum is included in the pages that follow. This wallboard industry and only a small amount was used guide is also available online at http://ohioline.osu. in agriculture. However, FGD gypsum is suitable for edu. agricultural uses and, similar to mined gypsum, can The purpose of this management guide is to provide enhance crop production. As with other fertilizers and general information about gypsum, especially FGD agricultural amendments, FGD gypsum must be used gypsum, as a soil amendment in Ohio as well as other appropriately to avoid potential negative impacts on places where FGD gypsum is available as a resource. both agricultural production and the environment. In This information will be useful for crop producers, soil many respects, there are similarities between the agri- and crop consultants, horticulturists, environmental cultural use of FGD gypsum and nitrogen fertilizers in consultants, environmental regulatory agents, and that both can provide crop production benefits but, if FGD gypsum producers and marketers. improperly used, can also lead to negative environmental impacts.

4 Gypsum as an Agricultural Amendment: General Use Guidelines Sources and Properties of Gypsum

Gypsum is a soluble source of the essential plant nutri- Combustion of coal produces 52% of our national need ents, calcium and sulfur, and can improve overall for electricity. During combustion, fly ash and bottom plant growth. Gypsum amendments can also improve ash are produced (Figure 1-2). If the coal contains the physical properties of some soils (especially heavy appreciable amounts of sulfur, sulfur dioxide is also clay soils). Such amendments promote soil aggregation produced, and the Clean Air Act Amendments of 1990 and thus can (1) help prevent dispersion of soil parti- restrict sulfur dioxide emissions into the atmosphere cles, (2) reduce surface crust formation, (3) promote from coal-fired facilities. This has spurred the develop- seedling emergence, and (4) increase water infiltration ment of flue gas desulfurization (FGD) systems that rates and movement through the soil profile. It can scrub the sulfur dioxide out of the flue gases and also reduce erosion losses of soils and nutrients and successfully bring utilities into regulatory compliance. reduce concentrations of soluble phosphorus in surface These FGD systems can generate large quantities of water runoff. Chemical properties improved by appli- products, including gypsum (Figure 1-2), which must cation of gypsum include the mitigation of subsoil be placed in landfills, deposited in surface impound- acidity and aluminum toxicity. This enhances deep ments, or beneficially recycled. rooting and the ability of plants to take up adequate supplies of water and nutrients during drought periods. Gypsum is the most commonly used amendment for sodic soil reclamation and can also be included as a component in synthetic soils for nursery, greenhouse, and landscape use. These multiple uses of FGD gypsum represent a great potential to provide benefits to agricultural and horticultural users. Several possible sources of gypsum for agricultural use are currently available in the United States. These include mined gypsum from geologic deposits, phos- phogypsum from wet-acid production of phosphoric acid from rock phosphate, recycled casting gypsum from various manufacturing processes, recycled wallboard gypsum, and flue gas desulfurization (FGD) Figure 1-2. Increase of total coal combustion products (CCPs) gypsum from power plants. FGD gypsum represents a including fly ash (FA), bottom ash (BA), boiler slag (BS), and new and large volume source and is produced when flue gas desulfurization (FGD) materials from 1966 to 2006. coal is burned to produce electricity, heat, or other (American Coal Ash Association, 2010.) forms of energy (Figure 1-1). Flue gas desulfurization (FGD) gypsum is created in limestone-forced oxidation scrubbers that remove sulfur dioxide from the flue gas stream after coal combustion. In general, a wet scrubbing process first exposes the flue gases to a slurry of hydrated lime. Capture of SO₂ by the lime slurry initially forms calcium sulfite (CaSO₃•0.5H₂O). Forcing additional air into the system oxidizes the calcium sulfite and converts it into gypsum, i.e., CaSO₄•2H₂O (Figure 1-3). During and after the oxidation process, washing of the by-product can remove some water-soluble elements such as boron (B). Also, in some cases, removal of fines can decrease mercury (Hg) concentrations. The final step of the process involves partial removal of water by Figure 1-1. Flue gas desulfurization (FGD) product is created a combination of centrifugation and vacuum filtration. by a scrubber that removes sulfur dioxide (SO₂) from the flue The gypsum that is recovered is high quality and suit- gas stream when energy sources containing high concentra- able for industrial (e.g., wallboard) and agricultural tions of sulfur are burned. (Norton and Rhoton, 2007.) uses.

Gypsum as an Agricultural Amendment: General Use Guidelines 5 Different sources of gypsum have specific mineralogical, physical, and chemical properties. Properties of FGD gypsum are often compared with results for the same measurements that are obtained for mined gypsum that is currently used in agriculture. Mineral- ogical and physical properties of FGD gypsum from the W. H. Zimmer Station of Duke Energy (Moscow, Ohio) and mined gypsum from the Kwest Group (Port Clinton, Ohio) are shown in Table 1-2. The mineral composition of FGD gypsum and mined gypsum is predominantly CaSO₄•2H₂O. Occasionally, FGD gypsum contains minor amounts of quartz (SiO₂). Figure 1-3. Schematic of the scrubbing process to produce Mined gypsum contains both quartz and dolomite FGD gypsum. (Dontsova et al., 2005.) [CaMg(CO₃)₂]. FGD gypsum usually possesses a much smaller and more uniform particle size (more than 95% < 150 microns) than agricultural mined gypsum Production of FGD gypsum has gradually increased that is granulated to produce a final size of 2–4 mm. over the past several years (Table 1-1). In 2008, approx- However, FGD gypsum can also be processed to form imately 18 million tons of FGD gypsum were produced larger-sized granules. of which 60% (10.6 million tons) was used—mainly in wallboard. Less than 2% of the total FGD gypsum production was used in agriculture. However, annual Table 1-2. Some Mineralogical and Physical Proper- production of FGD gypsum is expected to double in 10 ties of FGD Gypsum from the W. H. Zimmer Station of years as more coal-fired power plants come online and Duke Energy (Moscow, Ohio) and Mined Gypsum from as new scrubbers are added to existing power plants to the Kwest Group (Port Clinton, Ohio). (Dontsova et al., comply with the EPA’s Clean Air Amendments and 2005.) other requirements. Existing uses of FGD gypsum will FGD Mined Property Unit be unable to consume all of the new FGD gypsum that Gypsum Gypsum will be created. Because it is well known that mined Gypsum, Gypsum, gypsum can improve soil properties and water Minerals Present Quartz, Quartz management and can enhance agricultural produc- Dolomite tion, there is great interest in using the high-quality Water content % 5.5 0.38 FGD gypsum produced by utilities in place of mined gypsum. CaSO4•2H2O % 99.6 87.1 Insoluble residue % 0.4 13 Particle size Table 1-1. FGD Gypsum Production, Total Use, and > 250 Microns % 0.14 100 Agricultural Use from 2003 to 2008 in the United States. (American Coal Ash Association, 2010.) 150–250 Microns % 3.2 0 105–150 Microns % 33 0 FGD Gypsum Year Total Use Agricultural Use Production 74–105 Microns % 33 0 Short Tons Short Tons Short Tons < 74 Microns % 31 0 2008 17,755,000 10,653,000 279,000 2007 12,300,000 9,228,000 115,000 The chemical composition of FGD gypsum is influ- 2006 12,100,000 9,561,000 168,000 enced by the type of coal, scrubbing process, and sorbent used in the desulfurization process. The FGD 2005 11,975,000 9,268,000 362,000 gypsum can have a purity as high as 99.6% (Table 1-2). 2004 11,950,000 9,045,000 131,000 Concentrations of other chemical elements in FGD 2003 11,900,000 8,299,000 33,000 gypsum from the W. H. Zimmer Station of Duke

6 Gypsum as an Agricultural Amendment: General Use Guidelines Energy (Moscow, Ohio) and in mined gypsum from References the Kwest Group (Port Clinton, Ohio) are also shown American Coal Ash Association. 2010. ACAA Coal (Table 1-3). Combustion Products Survey. http://www. acaa-usa.org/displaycommon. Table 1-3. Chemical Properties of FGD Gypsum from cfm?an=1&subarticlenbr=3. the W. H. Zimmer Station of Duke Energy (Moscow, Dontsova, K, Y. B. Lee, B. K. Slater, and J. M. Bigham. Ohio) and Mined Gypsum from the Kwest Group (Port 2005. Ohio State University Extension Fact Sheet Clinton, Ohio). (Dontsova et al., 2005.) ANR-20-05. Gypsum for Agricultural Use in Element (Unit) FGD Gypsum Mined Gypsum Ohio—Sources and Quality of Available Products. http://ohioline.osu.edu/anr-fact/0020.html. Plant Macronutrients National Atmospheric Deposition Program. 2010. Calcium (Ca), (%) 24.3 24.5 NADP/NTN Monitoring Location OH71. Sulfur (S), (%) 18.5 16.1 http://nadp.sws.uiuc.edu/sites/siteinfo. Nitrogen (N), (ppm) 970 asp?net=NTN&id=OH71. Phosphorus (P), (ppm) < 1.0 30 Norton, L. D. and F. Rhoton. 2007. FGD Gypsum Potassium (K), (ppm) < 74 3,600 Influences on Soil Surface Sealing, Crusting, Infiltration and Runoff. Presented at the workshop Magnesium (Mg), (ppm) 200 26,900 on Agricultural and Industrial Uses of FGD Plant Micronutrients (ppm) Gypsum. October 2007. Atlanta, Ga. http://library. Boron (B) 13 99 acaa-usa.org/5-FGD_Gypsum_Influences_on_ Copper (Cu) < 0.38 < 0.60 Soil_Surface_Sealing_Crusting_Infiltration_and_ Iron (Fe) 150 3,800 Runoff.pdf. Manganese (Mn) 0.62 225 Molybdenum (Mo) 3.2 < 0.60 Nickel (Ni) < 3.0 < 0.60 Zinc (Zn) 1.2 8.7 Elements of Environmental Concern (ppm) Arsenic (As) < 11 462 Barium (Ba) 5.5 76 Cadmium (Cd) < 1.0 < 0.12 Chromium (Cr) < 1.0 10.4 Lead (Pb) < 5.0 100 Selenium (Se) < 25 < 0.60

Gypsum as an Agricultural Amendment: General Use Guidelines 7 Properties of Gypsum That Provide Benefits for Agricultural Uses

To make recommendations for gypsum use in agricul- lizes rather slowly, gypsum can provide continual ture, it is important that we have a good under- release of sulfur to the soil for more than just the year standing of its composition and properties. Composi- it is applied. Use of gypsum as a sulfur fertilizer to tion of pure gypsum (CaSO₄•2H₂O) is 79% calcium enhance crop production in sulfur deficient soils has sulfate (CaSO₄) and 21% water (H₂O). Pure gypsum been proved for many crops such as corn, soybean, contains 23.3% calcium (Ca) and 18.6% sulfur (S). canola, and alfalfa (Figure 2-2). Gypsum is moderately soluble in water (2.5 g per L) or approximately 200 times greater than lime (CaCO₃). This makes the calcium in gypsum more mobile than the calcium in lime and allows it to more easily move through the soil profile.

FGD Gypsum as a Source of Plant Nutrients For many years, crops received more than enough sulfur from rainfall, but monitoring of sulfur deposited by rainfall onto soil has revealed significant decreases in sulfur inputs. In 1979 about 31 lbs of sulfur per acre were deposited onto our soil in Ohio, and this decreased to about 16 lbs of sulfur per acre in 2007 (Figure 2-1). This decrease—coupled with other decreases in S inputs due to the use of highly concen- trated fertilizers containing little or no sulfur, inten- Figure 2-2. Gypsum as a sulfur fertilizer to enhance alfalfa sive cropping systems, and increased crop yields that production. Gypsum was an early form of fertilizer used in result in more sulfur removal from the soil every the United States and is an excellent source of calcium and year—is leading to more and more reports of sulfur sulfur. deficiencies in crops. Calcium moves very slowly, if at all, from one plant part to another, and fruits at the end of the transport system get too little. Calcium must, therefore, be constantly available to the roots. Additions to soil of a good source of calcium, such as gypsum, can improve the quality of horticultural crops (Sumner and Larri- more, Heckman, 2008; Scott et al., 1993; Shear, 1979). Root and orchard crops seem especially responsive to calcium. For example, use of gypsum as a calcium fertilizer for peanuts is well known in the southeastern United States, and adequate quantities of calcium must be present in the pegging zone for the proper development of disease-free peanuts (Figure 2-3). Root rot of avocado trees caused by Phytophthora, blossom-end rot of watermelon and tomatoes, and bitter pit in Figure 2-1. Decline of total sulfur deposition in north central apples are also partially controlled by gypsum (Scott et Ohio (Wooster, Ohio) from 1979 to 2008. The solid line is the al., 1993; Shear, 1979). trend line that is evident during these years. (National Atmo- spheric Deposition Program, 2010.) FGD Gypsum to Improve Soil Physical Properties Gypsum is one of the earliest forms of fertilizer used Soil structure is defined as the arrangement of primary in the United States. It has been applied to agricultural mineral particles and organic substances into larger soils for more than 250 years. Because gypsum solubi- units known as aggregates with their inter-aggregate

8 Gypsum as an Agricultural Amendment: General Use Guidelines pore system. Soil structure has been shown to influ- Soil crusting is the destruction of surface soil structure ence a wide variety of soil processes including water by raindrop impact, resulting in a surface layer and chemical transport, soil aeration and thermal enriched with individual soil particles and micro- regime, erosion by wind and water, soil response to aggregates. A serious consequence of crusting is mechanical stress, seedling germination, and root surface sealing caused by the destruction of the inter- penetration. aggregate pore system in the thin layer at the interface between the soil and the atmosphere. This surface sealing reduces water infiltration and gaseous exchange with the atmosphere and can also have an adverse effect on seedling emergence (Figure 2-6).

Figure 2-4. Gypsum as a soil amendment to improve soil physical properties. Addition of soluble Ca can overcome the dispersion effects of Mg or Na ions and help promote floccula- Figure 2-3. Gypsum as a calcium fertilizer to enhance peanut tion and structure development in dispersed soils. (Illustra- production. (Sumner, 2007; Tillman et al., 2010.) tion kindly provided by Dr. Jerry Bigham, The Ohio State University.)

Many soils from semiarid to humid regions have an unstable structure, which makes them susceptible to erosion and difficult to manage. These soils have a tendency to disperse and form a stable suspension of particles in water. As a result, they develop a more compacted structure, particularly at or near the soil surface. Clay dispersion is caused by the mutual repul- sion between the clay particles (Figure 2-4), which results from the presence of extensive negative electric fields surrounding them (Dontsova et al., 2004). Flocculation is the opposite process, where the electric double layer is sufficiently compressed so that attractive forces allow coagulation of the individual clay particles into microaggregates. Application of gypsum can reduce dispersion (Figure 2-4) and promote floc- Figure 2-5. Infiltration rate for a Blount soil with and without culation of soils. Flocculation is a necessary condition surface-applied gypsum. Gypsum can serve as a soil amend- for the formation and stabilization of soil structure. ment to improve soil physical properties and water infiltration This increases water infiltration and percolation and percolation. (Illustration kindly provided by Dr. Darrell (Figure 2-5 and Dontsova et al., 2004; Norton et al., Norton, USDA.) 1993; Norton, 2008), thus reducing soil erosion and improving water quality.

Gypsum as an Agricultural Amendment: General Use Guidelines 9 of high levels of exchangeable aluminum (Figure 2-7). Subsoil acidity prevents root exploitation of nutrients and water in the subsoil horizons. Agricultural lime is recommended for correction of soil acidity and low soil pH. Whereas the beneficial effects of calcitic lime are mostly limited to the zone of incorporation, surface applications of gypsum may affect soil physical and chemical properties at depth. This is because of gypsum’s much greater solubility compared to lime (Figure 2-8).

Figure 2-6. Dispersion of soil particles and then surface drying creates a crust that impedes seedling emergence. Gypsum as a soil amendment can improve soil physical properties to prevent dispersion and surface crust formation. (Dontsova et al., 2005; Norton et al., 1993.)

Surface crust strength is largely dependent on clay and moisture content. Gypsum helps reduce the dispersion 3+ of the clay that leads to surface crust formation and Figure 2-7. Effects of aluminum (Al ) on growth of fescue. also slows the rate of surface drying (Norton et al., (Illustration adopted from Buckman and Brady (1969) and 1993; Norton and Rhoton, 2007). Thus both the rate of kindly provided by Dr. Jerry Bigham, The Ohio State crust development and final strength will be affected University.) by gypsum additions leading to improved seedling emergence and establishment and in the reduction of modulus of rupture and resistance to penetration. The expected outcome of reducing soil crust formation is improved crop and pasture yields. Field studies in various locations around the world have indicated that the yields of crops can be significantly increased by gypsum, due in part to improved crop emergence and increased air and water entry into the soil. Gypsum is the most commonly used amendment for sodic soil reclamation. The basis for this is that gypsum provides Ca that can exchange with Na and Mg, thus leading to flocculation of soil particles. This promotes better overall structure development in these Figure 2-8. Gypsum as a soil amendment to remediate highly dispersed soils so that sufficient infiltration and subsoil acidity. Gypsum is 200 times more soluble than percolation of water into and through the soil profile lime and calcium and sulfur movement into soil profiles is can take place. enhanced by the addition of gypsum. (Sumner and Larri- more, 2006.) Gypsum to Improve Soil Chemical Properties Gypsum applications to Ca-deficient soils in humid The detrimental effects on plant growth of subsoil regions have shown beneficial effects because of Ca acidity, particularly at high levels of exchangeable 3+ movement into the subsoil (Figure 2-9 and Farina and aluminum (Al ), are well known. The lower the soil Channon, 1988; Stehouwer et al., 1999; and Toma et pH, the greater the concentration of soluble and avail- al., 1999), thereby improving root growth and lowering able aluminum. For many plants growing in acid soils, water stress. This improvement in crop response to it is not the pH that is especially toxic, but the presence gypsum use in soils with acid subsoils is not due to a

10 Gypsum as an Agricultural Amendment: General Use Guidelines Figure 2-9. Calcium and sulfur movement into soil profiles is enhanced by the addition of gypsum. These data were obtained six months after gypsum application. (Chen et al., 2005.)

change in pH, as gypsum is a neutral salt and not a liming agent. Therefore, its effect on surface or subsoil pH is relatively modest. However, FGD gypsum can ameliorate the phytotoxic conditions arising from excess soluble aluminum in acid soils by reacting with Al3+, thus removing it from the soil solution and greatly reducing its toxic effects (Figure 2-10 and Shainberg et al., 1989; Smyth and Cravo, 1992). Over- coming the effects of subsurface aluminum toxicity leads to improved deep rooting (Figures 2-8, 2-10, and 2-11) so that crops can take up water and nutrients from subsoil layers. This can greatly increase the supply of water and nutrients to crops. This is especially important in the dry season of arid areas, and a positive response to FGD gypsum is often greatest in moisture stress conditions.

Figure 2-11. Removal of subsoil acidity due to Al3+ can promote deeper rooting of plants. (Illustration kindly provided by Dr. Jerry Bigham, The Ohio State University.)

Figure 2-10. Soluble aluminum (Al3+) is toxic to plants. Gypsum can react with Al3+, thus removing it from the soil solution and greatly reducing its toxic effects on plant roots. (Illustration kindly provided by Dr. Jerry Bigham, The Ohio State University.)

Gypsum as an Agricultural Amendment: General Use Guidelines 11 References Buckman, H. O. and N. C. Brady. 1969. The Nature and Shainberg, I., M. E. Sumner, W. P. Miller, M. P. W. Properties of Soils. MacMillan, New York, 7th Farina, M. A. Pavan, and M. V. Fey. 1989. Use of Edition. 653 p. gypsum on soils. A review. Advances in Soil Brenes, E. and R. W. Pearson. 1973. Root responses of Science 9:1–111. three Gramineae species to soil acidity in an Shear, C. B. (Editor). 1979. Calcium nutrition of Oxisol and an Ultisol. Soil Science 116:295–302. economic crops (Special Issue). Communications Chen, L., Y. B. Lee, C. Ramsier, J. Bigham, B. Slater, in Soil Science and Plant Analysis 10:1–501. and W. A. Dick. 2005. Increased crop yield and Smyth, T. J. and S. Cravo. 1992. Aluminum and economic return and improved soil quality due to calcium constraints to continuous crop produc- land application of FGD-gypsum. In: Proceedings tion in a Brazilian Amazon soil. Agronomy Journal of the World of Coal Ash, April 11–15, 2005. 84:843–850. Lexington, Ky. Stehouwer, R. C., W. A. Dick, and P. Sutton. 1999. Dontsova, K. M., L. D Norton, C. T. Johnston, and J. Acidic soil amendment with a magnesium- M. Bigham. 2004. Influence of exchangeable containing fluidized bed combustion by-product. cations on water adsorption by soil clays. Soil Agronomy Journal 91:24–32. Science Society of America Journal 68:1218–1227. Sumner, M. E. 2007. Soil chemical responses to FGD Dontsova K., Y. B. Lee, B. K. Slater, and J. M. Bigham. gypsum and their impact on crop yields. Presented 2005. Ohio State University Extension Fact Sheet at the workshop on Agricultural and Industrial ANR-20-05. Gypsum for Agricultural Use in Uses of FGD Gypsum. October 2007, Atlanta, Ga. Ohio—Sources and Quality of Available Products. http://library.acaa-usa.org/3-Soil_Chemical_ http://ohioline.osu.edu/anr-fact/0020.html. Responses_to_FGD_Gypsym_and_Their_ Farina, M. P. W. and P. Channon. 1988. Acid-subsoil Impact_on_Crop_Yields.pdf. amelioration: II. Gypsum effects on growth and Sumner, M. E. and L. Larrimore. 2006. Use of gypsum subsoil chemical properties. Soil Science Society of for crop production on southeastern soils. America Journal 52:175–180. Presented at the workshop on Research and Norton, L. D. 2008. Gypsum soil amendment as a Demonstration of Agricultural Uses of Gypsum management practice in conservation tillage to and Other FGD Materials. September 2006, St. improve water quality. Journal of Soil and Water Louis, Mo. http://www.oardc.ohio-state.edu/ Conservation 63:46A–48A. agriculturalfgdnetwork/workshop_files/ presentation/Session1/Larrimore%20-%20 Norton, L. D. and F. Rhoton. 2007. FGD gypsum Gypsum%20for%20Crop%20Production%20 influences on soil surface sealing, crusting, on%20Southeastern%20Soils.ppt. infiltration and runoff. Presented at the workshop on Agricultural and Industrial Uses of FGD Tillman, B. L., C. L. Mackowiak, G. Person, and M. W. Gypsum. October 2007, Atlanta, Ga. http://library. Gomillion. 2010. Variation in response to calcium acaa-usa.org/5-FGD_Gypsum_Influences_on_ fertilization among four runner-type peanut culti- Soil_Surface_Sealing_Crusting_Infiltration_and_ vars. Agronomy Journal 102: 469–474. Runoff.pdf. Toma, M., M. E. Sumner, G. Weeks, and M. Saigusa. Norton, L. D., I. Shainberg, and K. W. King. 1993. 1999. Long-term effects of gypsum on crop yield Utilization of gypsiferous amendments to reduce and subsoil chemical properties. Soil Science surface sealing in some humid soils of the eastern Society of America Journal 63:891–895. USA. In: J. W. A. Poesen and M. A. Newaring Westermann, D. T. 1975. Indexes of sulfur deficiency (Editors), Soil Surface Sealing and Crusting, in alfalfa. II. Plant analyses. Agronomy Journal Catena Supplement 24:77–92. 67:265–268. Scott, W. D., B. D. McCraw, J. E. Motes, and M. W. Smith. 1993. Application of calcium to soil and cultivar affect elemental concentration of watermelon leaf and rind tissue. Journal of the American Society of Horticultural Science 118:201–206.

12 Gypsum as an Agricultural Amendment: General Use Guidelines Agricultural and Land Application Uses of Gypsum

Application of mined gypsum to agricultural soils has Agricultural gypsum and two types of FGD products a long history (Crocker, 1922). Most farmers do not that contain calcium sulfate (CaSO₄) and calcium have experience in applying gypsum to their fields and sulfite (CaSO₃) were applied at 0, 14, and 60 lbs of do not know the value of gypsum. Also, information is sulfur per acre to an agricultural soil (Wooster silt lacking as to the best management practices associated loam) located near Wooster, Ohio. Growth of a new with using gypsum as an agricultural amendment. In planting of alfalfa (Medicago sativa L.) was increased this chapter, several specific examples of using gypsum 10 to 40% by the treatments compared to the untreated in agriculture and for other land applications are control (Chen et al., 2005). Also at Wooster, increased introduced and briefly described. As previously men- alfalfa growth of 18% was associated with additions of tioned in Chapter 1, a readily available source of gyp- gypsum for the combined years of 2000–2002 (Figure sum for agricultural use in Ohio and the United States 3-1). In a further study, mined gypsum and the FGD is FGD gypsum. products mentioned earlier were applied at 0, 7, 14, and 21 lbs of sulfur per acre to five established alfalfa Gypsum as a Source of Plant Nutrients stands in different regions of Ohio. Mean alfalfa yields for Crops were increased 4.6% in 2001 and 6.2% in 2002 with sulfur treatments compared to the untreated control. An experiment was conducted in Ohio from 2002 to These results were statistically significant at the P ≤ 2005 to test a sulfur-by-nitrogen nutrient interaction 0.05 level (Chen et al., 2005). for corn production. The nitrogen was applied at rates of 0–210 lbs per acre as ammonium nitrate (NH₄NO₃) and sulfur was applied as FGD gypsum or another FGD product at the rate of 30 lbs per acre. Results indicated sulfur application significantly P( ≤ 0.05) increased the yield of corn compared to the no-sulfur control treatment in 2003 (Table 3-1). There was a sulfur-by-nitrogen interaction in 2004 and 2005 with sulfur increasing relative yields more at the low nitrogen application rates than at the high nitrogen rates. This result suggests that reduced nitrogen inputs and increased yield could offset the cost of applying gypsum and would also diminish the potential for Figure 3-1. Yields of alfalfa at Wooster, Ohio, (cumulative nitrate contamination of surface and ground waters. yields for years 2000–2002) were increased by the addition of gypsum, which improved the sulfur nutritional status of the Table 3-1. Effects of Nitrogen and Sulfur (S) Fertilizers soil. Different letters over each bar represent a significant on Corn Yields Grown in Wooster Silt Loam from 2003 difference at P ≤ 0.05. to 2005. (Chen et al., 2008.)

2003 2004 2005 Gypsum can also affect yields of other crops, and Nitrogen 30 lbs 30 lbs 30 lbs gypsum has been the most common calcium source No S No S No S S/acre S/acre S/acre for improving peanut production in the southeastern United States. Application of gypsum not only lbs/acre bushels per acre increases peanut yield but also improves peanut 0 127 149 105 122 66 61 quality. A study in Florida indicates that application of 60 161 180 139 149 67 90 gypsum at 0.5 ton per acre significantly increases the 90 162 181 148 158 76 85 yield and value of peanuts and the calcium concentration in peanut seeds (Table 3-2). 120 185 192 161 190 89 132 150 184 193 170 167 118 111 180 190 206 172 162 99 84 210 194 199 186 168 86 93

Gypsum as an Agricultural Amendment: General Use Guidelines 13 Table 3-2. Effect of FGD Gypsum on the Yield, Value, of water. The calcium in gypsum can bind with phos- and Calcium (Ca) Content of Peanuts Grown in phorus to form a calcium phosphate precipitate and Florida. (Sumner and Larrimore, 2006.) thus help improve water quality (Favaretto et al., 2006). Of several treatments to reduce phosphorus in Gypsum Yield Value Seed Ca surface water runoff, gypsum at approximately 2.0 tons/acre lbs/acre $/acre % tons per acre was found to be the most effective and 0 3,280 540 0.021 cost efficient (Figure 3-3 and Stout et al., 2000). It has 0.5 3,940 649 0.034 been suggested that use of gypsum, including FGD gypsum, could be included in a best management plan (BMP) for nutrient management of manures from Gypsum to Improve Soil Physical large animal production facilities. Properties Gypsum has been shown to improve surface infiltration rates by inhibiting or delaying surface seal formation as was described in the previous chapter. A field study was conducted using FGD gypsum at 1–2 tons per acre to improve infiltration in a poorly drained soil in Indiana, and the result is shown in Figure 3-2 (Norton and Rhoton, 2007). There was greater ponding of water in the control field than in the FGD gypsum-treated field. Water ponding restricts air exchange with the atmosphere and leads to poor crop stand. Figure 3-3. Effect of gypsum on runoff phosphorus. DRP is dissolved reactive phosphorus. (Brauer et al., 2005.)

Gypsum to Improve Soil Chemical Properties A study in Brazil indicated that applications of gypsum into the plow layer reduced subsurface aluminum toxicity and improved deep rooting so that water and nutrient uptake by corn, wheat, soybean, sorghum, and leuceana (a forage legume) were dramat- Figure 3-2. Application of FGD gypsum increases water infil- ically improved (Ritchey et al., 1995). For example, the tration and percolation. Foreground is the gypsum applica- percentage of corn roots found below 45-cm depth tion section, and background is the control section. (Norton increased by more than 600% with the addition of 2.7 and Rhoton, 2007.) tons per acre or more of gypsum. Corn, wheat, sorghum, and leuceana yields were also increased by 45, 50, 24, and 50% over the control, respectively. A Gypsum application to soil can reduce soil erosion by study in Mississippi indicated that application of FGD flocculating clay particles so that they settle out of gypsum at 4.4 tons per acre ameliorated subsoil acidity surface water and thus are less prone to be moved and increased cotton yield (Table 3-3) and overall offsite. Many soils in the United States have also cotton quality. Work in South Africa on corn has also become highly enriched in soluble phosphorus. This shown yield benefits when gypsum was applied to help occurs on soil surrounding animal production facili- overcome subsoil acidity problems (Farina et al., ties when heavy applications of manure or fertilizer 2000a; 2000b). phosphorus are applied without proper soil testing. This phosphorus, if moved off the field into receiving Gypsum is the most commonly used amendment for water bodies, can cause eutrophication, which is sodic soil reclamation. A field study was conducted in defined as excessive nutrients in a lake or other body China using gypsum to remediate a heavy sodic soil.

14 Gypsum as an Agricultural Amendment: General Use Guidelines Very few crops could grow on the site before reclamation in 2000. Gypsum was applied in 2001 at a rate of 26 tons per acre, and corn was planted in 2002 and 2003. Figure 3-4 shows the growth of corn plants in the section treated with gypsum (background) and in a section of the control treatment (foreground).

Table 3-3. Effect of FGD Gypsum on the Yield of Cotton in an Acid Subsoil in Mississippi. (Sumner and Larrimore, 2006.)

Gypsum Treatment Seed Cotton Lint tons/acre lbs/acre Figure 3-5. FGD gypsum as a component of synthetic soils for 0 1,660 612 nursery and greenhouse use. Tomato seedlings in the left pot 4.4 1,990 729 were growing in a commercial medium, and those in the right pot were growing in the medium containing FGD gypsum.

In 2004, we created a mix containing 20% FGD gypsum, 33% bottom ash, 12% biosolids, 23% dairy manure compost, and 12% sphagnum peat. This Gypsum medium was used to test for nursery growth of red treated sunset maple trees in a pot-in-pot production system. (26 tons/acre) The goal was to produce healthy and marketable nursery crops with minimum potential negative environmental impacts. The mix containing FGD gypsum Untreated was compared with commercial mixes at the Willoway Nursery site in Avon, Ohio. In this study, the growth of maple trees in the mix containing FGD gypsum was not better, but similar, to that in the commercial Figure 3-4. Gypsum as a soil amendment to remediate sodic mixes. or sodium-affected soils. Foreground is the control section, and background is the gypsum application section. (Xu, Gypsum for Landscape and Sports Field Use 2006.) Turfgrasses are perennials, and turf management often needs to ameliorate the effects of acidity that can accu- mulate in the soil profile due to nitrogen fertilizer. Gypsum for Nursery, Greenhouse, However, agricultural lime only corrects acidity in the application layer. It cannot ameliorate the effects of Landscape, and Sports Field Use subsoil acidity without tilling the soil in which the turf is growing. Surface application of gypsum, which is As a Component of Plant Growth Media more soluble than agricultural lime, can provide In 2004, we combined FGD gypsum, bottom ash, and calcium and sulfur for grasses and ameliorate composts to create high-quality, low-cost marketable aluminum (Al3+) toxicity experienced by the grasses growth media for the nursery and landscape indus- growing in soils that often become acid because of tries. Figure 3-5 shows tomato (Lycopersicum escul- high nitrogen fertilizer inputs. An experiment entum) seedlings 35 days after planting when grown in conducted at Pennsylvania State University indicated a commercial medium compared to the medium that green cover was increased 6% by FGD gypsum containing gypsum, peat, compost, and bed ash applied at a rate of 7 tons per acre (Schlossberg, 2006). (Bardhan et al., 2005). The result indicated that the Figure 3-6 shows FGD gypsum being surface-applied medium containing FGD gypsum significantly to a golf course. enhanced the growth of tomato compared to the commercial medium.

Gypsum as an Agricultural Amendment: General Use Guidelines 15 References Bardhan, S., L. Chen, and W. A. Dick. 2005. Soilless media created from coal combustion products and organic composts: Environmental and chemical properties. In: Agronomy Abstracts. American Society of Agronomy, Madison, Wis. Brauer, D., G. E. Aiken, D. H. Pote, S. J. Livingston, L. D. Norton, T. R. Way, and J. H. Edwards. 2005. Amendment effects on soil test phosphorus. Journal of Environmental Quality 34:1682–1686. Chen, L., W. A. Dick, and D. Kost. 2008. Flue gas desulfurization products as sulfur sources for corn. Soil Science Society of America Journal Figure 3-6. FGD gypsum being applied to the soil surface of a 72:1464–1470. golf course. (Sumner and Larrimore, 2006.) Chen, L., W. A. Dick, and S. Nelson Jr. 2005. Flue gas desulfurization products as sulfur sources for alfalfa and soybean. Agronomy Journal 97:265–271. Other Uses of Gypsum in Agriculture Crocker, W. 1922. History of the Use of Agricultural A report by Dick et al. (2006) summarizes 20 different Gypsum. Gypsum Industries Association, Chicago, potential agricultural and other land application uses Ill. of gypsum. As previously noted, gypsum has been Dick, W. A., D. Kost, and N. Nakano. 2006. A review of used to enhance the yield and quality of some horti- agricultural and other land application uses of flue cultural crops. For example, gypsum decreases storage gas desulfurization products. Report 101385, rots of cantaloupe and tomato (Sumner and Larri- Electric Power Research Institute, Palo Alto, Calif. more, 2006; Scott et al., 1993; Shear, 1979). One study 97 p. in Georgia found that application of FGD gypsum at the rate of 1,000–3,000 lbs per acre increased canta- Farina, M. P. W., G. R. Thibaud, and P. A. Channon. loupe growth, fruit yield, skin calcium, and storage 2000a. A comparison of strategies for ameliorating time (Sumner and Larrimore, 2006). A study in subsoil acidity. I. Long-term growth effects. Soil Mississippi and Alabama indicated that application of Science Society of America Journal 64:646–651. gypsum at 4,000 lbs per acre increased tomato yield by Farina, M. P. W., G. R. Thibaud, and P. A. Channon. 20% and increased shelf life. 2000b. A comparison of strategies for ameliorating subsoil acidity. II. Long-term soil effects. Soil Science Society of America Journal 64: 652–658. Favaretto, N., L. D. Norton, B. C. Joern, and S. M. Brouder. 2006. Gypsum amendment and exchangeable calcium and magnesium affecting phosphorus and nitrogen in runoff. Soil Science Society of America Journal 70:1788–1796. Heckman, J. R. 2008. Can soil fertility influence tomato flavor? New Jersey Annual Vegetable Meeting Proceedings. p. 11–13. http://www. njfarmfresh.rutgers.edu/documents/ CanSoilFertilityImproveTomatoFlavor.pdf.

16 Gypsum as an Agricultural Amendment: General Use Guidelines Norton, L. D. and F. Rhoton. 2007. FGD gypsum Shear, C. B. (Editor). 1979. Calcium nutrition of influences on soil surface sealing, crusting, economic crops (Special Issue). Communications infiltration and runoff. Presented at the workshop in Soil Science and Plant Analysis 10:1–501. on Agricultural and Industrial Uses of FGD Stout, W. L., J. Landa, and A. N. Sharpley. 2000. Effec- Gypsum. October 2007, Atlanta, Ga. http://library. tiveness of coal combustion by-products in acaa-usa.org/5-FGD_Gypsum_Influences_on_ controlling phosphorus export from soils. Journal Soil_Surface_Sealing_Crusting_Infiltration_and_ of Environmental Quality 29:1239–1244. Runoff.pdf. Sumner, M. E. and L. Larrimore. 2006. Use of gypsum Ritchey, K. D., C. M. Feldhake, R. B. Clark, and D. M. for crop production on southeastern soils. G. de Sousa. 1995. Improved water and nutrient Presented at the workshop on Research and uptake from subsurface layers of gypsum- Demonstration of Agricultural Uses of Gypsum amended soils. In: D. L. Karlen, R. J. Wright, and and Other FGD Materials. September 2006, St. W. O. Kemper (Eds.). Agricultural Utilization of Louis, Mo. http://www.oardc.ohio-state.edu/ Urban and Industrial By-Products. ASA Special agriculturalfgdnetwork/workshop_files/ Publication No. 58, ASA, CSSA, and SSSA, presentation/Session1/Larrimore%20-%20 Madison, Wis. Gypsum%20for%20Crop%20Production%20 Schlossberg, M. 2006. Turfgrass growth and water use on%20Southeastern%20Soils.ppt. in gypsum-treated ultisols. Presented at the Xu, X. 2006. Soil reclamation using FGD byproduct in workshop on Research and Demonstration of China. Presented at the workshop on Research and Agricultural Uses of Gypsum and Other FGD Demonstration of Agricultural Uses of Gypsum Materials. September 2006, St. Louis, Mo. and Other FGD Materials. September 2006, St. http://www.oardc.ohio-state.edu/ Louis, Mo. http://www.oardc.ohio-state.edu/ agriculturalfgdnetwork/workshop_files/ agriculturalfgdnetwork/workshop_files/ presentation/Session1/Schlossberg-Turfgrass%20 presentation/Session1/Soil%20Amelioration%20 Growth%20and%20Water%20Use.ppt. %20by%20FGD%20Byproduct%20in%20China-1. Scott, W. D., B. D. McCraw, J. E. Motes, and M. W. pdf. Smith. 1993. Application of calcium to soil and cultivar affect elemental concentration of watermelon leaf and rind tissue. Journal of the American Society of Horticultural Science 118:201–206.

Gypsum as an Agricultural Amendment: General Use Guidelines 17 Gypsum Application

Determining the Appropriate because it can help identify soils that are low in avail- Application Rate able sulfur and guide decisions about sulfur fertilizer needs in crops for the next year. In order to make efficient use of gypsum to enhance crop production, it is necessary to be able to determine Another way to identify soils that may be deficient in the amount of gypsum that should be applied. The rate sulfur is through the application of a sulfur deficiency of gypsum application depends on the specific model. A database of the sulfur status of Ohio’s soils purposes for using gypsum for crop production and for crop growth was developed by combining inputs the farmer’s perception of return on investment. This from the atmosphere and organic matter with outputs is primarily a factor of increased revenue obtained due due to leaching and crop removal. The database is to increasing crop yields or improving fertilizer use organized by soil series within counties to predict the efficiency relative to the cost of transport and applica- sulfur status of a particular soil for crop growth. tion of the gypsum. Potential availability of sulfur to crops from soil can be predicted using the model. This model can be found For many land-application uses of gypsum, it is at http://www.oardc.ohio-state.edu/sulfurdef. It is important that the recommended rates are based on easy to use and a good tool to rapidly determine well-defined principles of soil and agronomic science. whether a soil may be deficient in available sulfur and If the source of gypsum is FGD gypsum, application at thus limit crop production. However, confirmation by a rate greater than predicted necessary may be inter- on-farm trials and/or crop tissue analysis is recom- preted as disposal and could also be harmful. This is mended. Details on how to conduct on-farm fertility similar to other types of agricultural inputs, such as trials have been provided by Sundermeier (1997). nitrogen fertilizer, if applied at excessive rates. Appli- cation at a rate less than that predicted as necessary Table 4-1. Harvest Removal of Sulfur (S) by Various may be ineffective for enhancing crop yields or Crops at Specific Yields and the Amount of Gypsum improving soil quality. According to the specific Needed to Replace the Removed Sulfur. (Dick et al., purpose for why gypsum is to be applied to soil, the 2008.) appropriate rates can vary greatly, from less than 100 lbs to several tons per acre each year. Gypsum Application Yield S Removed Application Rates of Gypsum as Sulfur Fertilizer Crop to Replace to Enhance Crop Production S Removed tons/acre lbs/acre lbs/acre Gypsum is a quality source of both calcium and sulfur for plant nutrition. Deficiencies of sulfur in crops are Corn grain 5.8 15 81 increasing due to a combination of factors (Dick et al., Sorghum 4.2 22 118 2006). These factors include increased crop yields that forage result in more sulfur removal from soil, reduced sulfur Wheat 2.4 7 38 inputs contained as by-products in other nutrient Canola 1.0 12 65 fertilizers, and decreased sulfur deposition from the atmosphere. Sulfur removed by various crops at Soybean 1.8 12 65 specific yields is presented in Table 4-1. Availability of Sunflower 1.7 6 32 sulfur to crops from soil is reduced due to plant Alfalfa 5.8 30 161 removal, and additional sulfur may need to be added Cool-season 4.0 16 86 to soil for improved growth of rotational crops. grass Plant testing has been used to assess the nutrient status Cotton 0.8 40 215 of crops. Sulfur concentrations in crop tissues are Peanut 2.0 21 113 usually decreased due to sulfur deficiency of the crop. Critical sulfur concentrations in crop plants are listed Rice 3.5 12 65 in Table 4-2. Critical levels will probably not be useful Sugar beet 30 45 242 for correcting sulfur nutritional needs in the current Orange 27 28 151 crop because of the difficulty of getting back in the Tomato 30 41 220 field in a timely manner to correct the sulfur deficiency. However, this information is important Potato 25 22 118

18 Gypsum as an Agricultural Amendment: General Use Guidelines Suggested application rates of gypsum as a fertilizer such as peanut—application rates can be as much as source of sulfur for specific crop requirements are 1,000–4,000 lbs per acre (Sumner, 2007). listed in Table 4-3. These rates are based upon Concentrations of sulfur and calcium in gypsum combining inputs from the atmosphere and organic usually range from 17–19% sulfur and 20–24% matter with outputs to leaching and crop removal. If calcium. The amounts of these nutrients that are added gypsum is applied as a calcium fertilizer instead of as a to soil at different application rates of gypsum (Table sulfur fertilizer—for example, to enhance the yield and 4-4) are based on values of gypsum having 18.6% quality of horticultural crops and especially root crops sulfur and 23.3% calcium.

Table 4-2. Critical Sulfur Concentrations in Crop Plants. (Dick et al., 2008.)

Concentration Crop Part Sampled Time of Sampling Deficient % Low % Sufficient % High % Alfalfa Top 15 cm Early bud < 0.20 0.20–0.25 0.26–0.50 > 0.50 Corn Ear leaf Silking < 0.10 0.10–0.20 0.21–0.50 > 0.50 Oats Top leaves Boost stage < 0.15 0.15–0.20 0.21–0.40 > 0.40 Soybean First trifoliate Early flower < 0.15 0.15–0.20 0.21–0.40 > 0.40 Barley YEB† Mid-late tillering 0.15–0.40 Canola YMB Prior to flowering 0.35–0.47 Cotton YMB Early flowering 0.20–0.25 Ryegrass Young herbage Active growth 0.10–0.25 Peanut YML Pre-flowering 0.20–0.35 Sugar cane Top visible dewlap Active growth 0.12–0.13 White clover Young herbage Active growth 0.18–0.30 Wheat YEB/YMB Mid-late tillering 0.15–0.40 Rice Whole top Maximum tillering 0.14 Rice Whole top Active tillering 0.23

†YEB, youngest emerged leaf blade; YMB, youngest mature leaf blade; and YML, youngest mature leaf.

Gypsum as an Agricultural Amendment: General Use Guidelines 19 Table 4-3. The Amount of Gypsum Application Needed Application Rates of Gypsum as a Soil Amend- to Supply Specific Amounts of Sulfur Nutrient to ment to Improve Physical and Chemical Properties Support the Growth of Various Crops. These of Soils Suggestions Are Broadly Based on the Amount of Gypsum can provide many physical and chemical Sulfur Removed at Harvest and Lost Due to Leaching. benefits to soil in addition to nutritional benefits. In Amount of some soils it can: (1) prevent dispersion of soil parti- Amount of Sulfur Gypsum cles, (2) reduce surface crust formation, (3) promote Application Crop Application seedling emergence, (4) increase water infiltration lbs/acre lbs/acre rates and movement into and through the soil profile, Corn grain 30 160 (5) reduce erosion losses of soils and nutrients and phosphorus concentrations in surface water runoff, Sorghum forage 40 220 and (6) mitigate subsoil acidity and aluminum toxicity. Wheat 30 160 An easy test to see if gypsum will physically benefit a Canola 30 160 soil is to take a teaspoon of soil and one-half ounce of Soybean 30 160 distilled or rain water in a small tube. Alternatively, Sunflower 15 80 one can place two tablespoons of soil in a straight- walled quart jar and fill it two-thirds full with water. Alfalfa 70 380 Shake up the soil in the water and then allow it to Cool-season 30 160 stand for two or more hours. If the upper liquid grass remains cloudy after two hours, the soil is likely to Cotton 100 540 respond to an application of gypsum. Application rates Peanut 50 270 of gypsum for improving soil physical properties are usually in the range of 1,000 to 5,000 lbs per acre Rice 30 160 (Brauer et al., 2006; Norton and Rhoton, 2007). In Sugar beet 100 540 some extreme cases, such as for sodic soils, higher Orange 60 320 rates may be justified. Tomato 100 540 Gypsum can also be used to improve the chemical Potato 50 270 properties of a soil. Predictions for the gypsum requirement (GR) for remediating subsoil acidity, magnesium-impacted soils, and sodic soils may be obtained using the equations shown in Table 4-5. For Table 4-4. Application Rates of Sulfur (S) and Calcium these applications, higher rates are often recom- (Ca) Calculated Based on the Amount of Gypsum mended than for overcoming nutrient deficiencies Application. because the calcium (primarily) needs to exchange with sodium or magnesium or leach downward to Gypsum S Ca replace aluminum. The calcium cannot be easily lbs/acre lbs/acre lbs/acre supplied by agricultural lime since the solubility of 50 9.3 12 agricultural lime is 200 times less than that of gypsum. Also, in the case of sodic soils, the pH is already very 100 19 23 high and an upward pH adjustment is not needed. For 1,000 (0.5 ton) 186 233 remediating acidity in acid subsoils (20–60 cm depth), 2,000 (1.0 ton) 372 466 application rates of gypsum usually vary from 2 to 10 5,000 (2.5 tons) 930 1,165 tons per acre. For remediating magnesium-dominated soils, application rates of gypsum usually range from 2 10,000 (5.0 tons) 1,860 2,330 to 5 tons per acre. Typical application on sodic clay 15,000 (7.5 tons) 2,790 3,495 soils ranges from 1 to 5 tons per acre every few years as 20,000 (10 tons) 3,720 4,660 needed. Gypsum may need to be reapplied every couple of years in wet climates or on irrigated fields as the gypsum will leach out of the soil profile.

20 Gypsum as an Agricultural Amendment: General Use Guidelines Table 4-5. Equations to Estimate the Gypsum Requirement (GR) for Remediating Subsoil Acidity, Magnesium Soils, and Sodic Soils.

Amendment Equation* Source Subsoil Acidity Ritchey GR (lbs/acre) = (–114 + 82.773A – 2.739A 2) × 0.893/0.186 Amendment s s et al., 1995 GR (lbs/acre) = [(% Mg base saturation – 20)/100 × CEC × 2000] + [(pH –7.2) × 2000] Magnesium or Hecht, 2006 Amendment GR (lbs/acre) = [(((ppm Mg/120)/CEC) – 0.20) × CEC × 2000] + [(pH –7.2) × 2000] GR (lbs/acre) = [(((ppm Na/230)/CEC) – 0.02) × CEC × 2000] + = Sodium Amendment Hecht, 2006 [(((ppm Mg/120)/CEC) – 0.20) × CEC × 2000] + [(pH –7.2) x 2000]

*As = (S sorbed)/(S in solution) after 2 grams of soil are shaken for 18 h with 20 mL of 0.75 mM CaSO4·2H2O solution. CEC is cation exchange capacity (meq/100g).

Application Rates of Gypsum for Nursery, granule can be applied directly to the soil surface Greenhouse, Landscape, and Sports Field Use using conventional dry material spinners or drop box Use of gypsum for nursery, greenhouse, landscape, spreaders (Figure 4-1). In cases where the gypsum is and sports fields is generally based on the same phys- in a powder form, application during strong windy ical and chemical properties as for agronomic crops. days should be avoided. If the desire is to move the However, rates used are generally higher due to the gypsum downward into the subsoil as quickly as inability to till the gypsum into the soil and to avoid possible and if there is a need to avoid and decrease annual or multiple applications. Application rates can erosion by wind and water, the gypsum should be vary greatly, from 5 to 20% of the medium for nursery immediately incorporated into the soil. and greenhouse crops and from 4,000 to 14,000 lbs per acre for landscape and sports turf fields (Bardhan et al., 2004; Schlossberg, 2007).

Summary of Recommended Gypsum Application Rates for Various Uses Figure 4-1. FGD gypsum can be applied directly to the soil Recommended rates, time of application, and method surface using conventional dry material spreaders. (From the of application of gypsum for various functions are FGD Network website: http://www.oardc.ohio-state.edu/ summarized in Table 4-6. For use of gypsum as a agriculturalfgdnetwork.) nutritional source of sulfur and calcium, application should be done annually. However, for some applications, especially where the higher rates are used, it is very likely that application will not be done annually. The time of application will also be different Instead application will occur initially at a high rate to depending on the reasons or benefits that are desired remediate a soil situation, and then, in subsequent for the use of gypsum. In reality, gypsum can be years, much lower maintenance rates would be applied during any season of the year, but other applied. considerations dictate the best times for application. Autumn applications can be made as soon as crops are Equipment and Other Land Application harvested from the field. Autumn applications provide Considerations for FGD Gypsum several advantages compared to other seasons. The fields are generally drier, making it easier to drive The method of applying gypsum to soil or for other heavy spreading equipment across the field without agricultural uses depends on the reason the gypsum damaging the soil. An autumn application allows time is being used. Usually, gypsum can be spread as for soil/gypsum reactions to take place so that the next either a solid or dissolved in irrigation water if year’s crop can better take advantage of the gypsum ground to a fine powder. For land application, application. gypsum sources in the form of either a powder or

Gypsum as an Agricultural Amendment: General Use Guidelines 21 In some cases, dissolving gypsum in irrigation water is courses, (4) promoting soluble calcium to fruit crops a preferred method of application for agricultural uses. and other plants to avoid low calcium fruit disorders However, for gypsum to go readily into solution, it like blossom end rot in tomatoes and bitter pit in must be finely ground to less than 200 to 300 mesh apples, (5) decreasing the length of time for soils to size. Application by water offers many benefits respond to gypsum application, and (6) increasing the including (1) increasing the solute concentration of uniformity of the gypsum application (Nature’s Way irrigation water to enhance water infiltration into soil, Resources, 2010). (2) decreasing the sodium absorption ratio (SAR) of If the soil has cracks, applying gypsum in irrigation saline irrigation water so that the irrigation water does water will allow the gypsum to penetrate further into not contribute to the sodicity of the soil by increasing the soil. The result will be that the effects of the appli- the exchangeable sodium percentage, (3) avoiding cation will be noted more rapidly and also will occur unsightly granules of gypsum lying on turf of golf deeper into the soil profile.

Table 4-6. Rate, Time, and Method of Application of Gypsum for Various Functions.

Suggested Rates of Application Suggested Suggested Function (lbs/acre) Time of Application Reference Application Method Low Normal High Chen et al., 2008 Sulfur fertilizer to enhance Soil surface or 100 300 500 Before planting DeSutter and crop production incorporated Cihacek, 2009 Calcium fertilizer to enhance Before peanut Grichar et al., crop production (especially 1,000 2,000 4,000 Soil surface pegging 2002 root crops, e.g., peanuts) Soil amendment to remediate 1–180 days 3,000 6,000 10,000 Soil surface Chen et al., 2005 subsoil acidity before planting 90–180 days Soil amendment to remediate before planting, Soil surface or 2,000 10,000 20,000 Xu, 2006 sodic or sodium-affected soils before rainy incorporated season Soil amendment to improve water quality (e.g., by reducing 1–180 days Norton and 1,000 6,000 9,000 Soil surface phosphorus concentrations in before planting Rhoton, 2007 surface water runoff) Soil amendment to improve soil 1–180 days physical properties and water 1,000 3,000 9,000 Soil surface Sumner, 2007 before planting infiltration and percolation Spring, As a lawn care product and Schlossberg, 4,000 8,000 14,000 summer, or Soil surface sport field application 2007 autumn Mixing As a component of synthetic Preparation of Bardhan 5% 10% 20% with other soils for nursery synthetic soils et al., 2004 components

22 Gypsum as an Agricultural Amendment: General Use Guidelines References Bardhan, S., L. Chen, and W. A. Dick. 2004. Plant edu/agriculturalfgdnetwork/workshop_files/ growth responses to potting media prepared from presentation/Session3/Hecht%20-%20Using%20 coal combustion products (CCPs) amended with Calcium%20Sulfate%20as%20a%20Soil%20 compost. In: Agronomy Abstracts. American Management%20Tool.ppt. Society of Agronomy, Madison, Wis. Nature’s Way Resources. 2010. Gypsum (CaSO₄). Brauer, D., G. Aiken, D. Pote, S. J. Livingston, L. D. http://www.natureswayresources.com/DocsPdfs/ Norton, T. R. Way, and J. H. Edwards. 2006. gypsum.doc. Effects of various soil amendments on soil test P Norton, L. D. and F. Rhoton. 2007. FGD gypsum values. Presented at the workshop on Research and influences on soil surface sealing, crusting, Demonstration of Agricultural Uses of Gypsum infiltration and runoff. Presented at the workshop and Other FGD Materials. September 2006, St. on Agricultural and Industrial Uses of FGD Louis, Mo. http://www.oardc.ohio-state.edu/ Gypsum. October 2007 in Atlanta, Ga. http:// agriculturalfgdnetwork/workshop_files/ library.acaa-usa.org/5-FGD_Gypsum_Influences_ presentation/Session1/Brauer%20-%20Soil%20 on_Soil_Surface_Sealing_Crusting_Infiltration_ Amendments%20and%20Soil%20Test%20P.ppt. and_Runoff.pdf. Chen, L., D. Kost, and W. A. Dick. 2008. Flue gas Ritchey, K. D., C. M. Feldhake, R. B. Clark, and D. M. desulfurization products as sulfur sources for G. de Sousa. 1995. Improved water and nutrient corn. Soil Science Society of America Journal uptake from subsurface layers of gypsum- 72:1464–1470. amended soils. In: D. L. Karlen, R. J. Wright, and Chen, L., Y. B. Lee, C. Ramsier, J. Bigham, B. Slater, W. O. Kemper (Eds.). Agricultural Utilization of and W. A. Dick. 2005. Increased crop yield and Urban and Industrial By-Products. ASA Special economic return and improved soil quality due to Publication No. 58, ASA-CSSA-SSSA, Madison, land application of FGD-gypsum. In: Proceedings Wis. of the World of Coal Ash, April 11–15, 2005. Schlossberg, M. 2007. Turfgrass response to surface- Lexington, Ky. applied gypsum. Presented at the workshop on DeSutter, T. M. and L. J. Cihacek. 2009. Potential agri- Agricultural and Industrial Uses of FGD Gypsum. cultural uses of flue gas desulfurization gypsum in October 2007 in Atlanta, Ga. http://library. the northern Great Plains. Agronomy Journal acaa-usa.org/3-Turfgrass_Response_to_Surface- 101:817–825. applied_Gypsum.pdf. Dick, W. A., D. Kost, and N. Nakano. 2006. A review of Sumner, M. E. 2007. Soil chemical responses to FGD agricultural and other land application uses of flue gypsum and their impact on crop yields. Presented gas desulfurization products. Report 101385, at the workshop on Agricultural and Industrial Electric Power Research Institute, Palo Alto, Calif. Uses of FGD Gypsum. October 2007 in Atlanta, 97 p. Ga. http://library.acaa-usa.org/3-Soil_Chemical_ Dick, W. A., D. Kost, and L. Chen. 2008. Availability of Responses_to_FGD_Gypsym_and_Their_ sulfur to crops from soil and other sources. In: J. Impact_on_Crop_Yields.pdf. Jez (Ed.). Sulfur: A Missing Link between Soils, Sundermeier, A. 1997. Guidelines for On-Farm Crops, and Nutrition. Agronomy Monograph 50. Research. Columbus, Ohio. Ohio State University ASA-CSSA-SSSA. p. 59–82. Madison, Wis. Extension Fact Sheet ANR-001-97, Columbus, Grichar, W. J., B. A. Besler, and K. D. Brewer. 2002. Ohio. http://ohioline.osu.edu/anr-fact/0001.html. Comparison of agricultural and power plant Xu, X. 2006. Soil reclamation using FGD byproduct in by-product gypsum for south Texas peanut China. Presented at the workshop on Research and production. Texas Journal of Agriculture and Demonstration of Agricultural Uses of Gypsum Natural Resources 15:44–50. and Other FGD Materials. September 2006, St. Hecht, B. 2006. Using calcium sulfate as a soil Louis, Mo. http://www.oardc.ohio-state.edu/ management. Presented at the workshop on agriculturalfgdnetwork/workshop_files/ Research and Demonstration of Agricultural Uses presentation/Session1/Soil%20Amelioration%20 of Gypsum and Other FGD Materials. September %20by%20FGD%20Byproduct%20in%20China-1. 2006, St. Louis, Mo. http://www.oardc.ohio-state. pdf.

Gypsum as an Agricultural Amendment: General Use Guidelines 23 Economic Considerations Related to Gypsum Use

The relationship between costs and benefits, or the A study of 51 experimental sites for peanut production cost/benefit ratio, is an important consideration for in Florida, Mississippi, Georgia, and Alabama indi- whether use of gypsum as a soil amendment will be cated application of FGD gypsum increased income at adopted or sustained. The costs associated with using 36 of the sites (Figure 5-1 and Table 5-2). A study in gypsum, including FGD gypsum, includes the costs of Mississippi (Sumner and Larrimore, 2006) indicated purchasing the material, transporting it from the site that application of gypsum at 2 tons per acre signifi- of generation to the site of use, and spreading it on the cantly increased tomato yield and value (Table 5-3). land. The benefits are most often associated with Similar studies for horticultural crops in Ohio have increased crop yields. not been conducted. A preliminary economic survey of eight farmers was conducted in northwestern Ohio. The farmers were selected as pairs, with one farmer in each pair using no-tillage and approximately one ton of gypsum per acre as part of the crop production system and the other nearby farmer on the same soil type using conventional tillage practices without gypsum. The survey was conducted at the end of two cropping years, and the costs of production and return above total costs were calculated in 2005. The results (Table 5-1) can compare these two cropping systems but cannot unequivocally attribute all of the differences to either only no-tillage or only gypsum. The differences in return above total cost were primarily attributed to Figure 5-1. Income response for application of FGD gypsum lower costs, and not crop yield, associated with the NT for peanut in the southeastern United States. (Sumner, 2007.) plus gypsum crop production system compared to the CT minus gypsum crop production system. More research is needed to determine the best soil types and management practices that lead to potential benefits of Table 5-2. Effect of FGD Gypsum on Peanut Yields and using gypsum as a soil amendment for enhancing crop Value in Florida, Mississippi, Georgia, and Alabama. yield and farm profitability. (Sumner and Larrimore, 2006.)

Rate of Yield Value Table 5-1. Total Costs and Return Above Total Costs State Gypsum for Two Different Management Systems (NT—no tons/acre lbs/acre $/acre tillage and CT—conventional tillage) for Corn and 0 3,280 540 Florida Soybean Production. (Chen et al., 2005.) 0.5 3,940 649 Return Above 0 2,940 503 Management Total Cost Crop Total Cost Mississippi System ($/acre)a 0.5 3,260 564 ($/acre)b 0 813 112 NT plus gypsum 321 17 Corn Georgia 1.0 1,210 185 CT minus gypsum 374 –28 2.0 1,290 198 NT plus gypsum 228 79 Soybean 0 4,100 754 CT minus gypsum 272 18 Alabama 0.5 5,410 995 a Includes fuel, machinery and equipment, land costs, management costs and labor. b The differences for soybean, but not corn, between the two management systems were significantly different at the 5% level of significance.

24 Gypsum as an Agricultural Amendment: General Use Guidelines Table 5-3. Effect of Gypsum on Tomato Yield and Electricity-producing utilities that rely on coal as an Value in Mississippi. energy source are a major source of FGD gypsum. Currently, most FGD gypsum is produced in the Gypsum Yield Value eastern United States. Transportation costs are a major tons/acre lbs/acre $/acre impediment to many agricultural uses of FGD 0 14,800 5,900 gypsum. Potential markets located in the western 2 17,700 7,070 United States may never become economically viable for FGD gypsum produced in the eastern United States unless FGD gypsum producers are located on Application of gypsum to ameliorate acid subsoil may navigational rivers or along rail lines. Barges offer an increase the yield and value of crops not only in the attractive way of moving materials and can be linked application year but even more so in the following to rail or truck transportation to move material. years. One example was increased yield and value of Generalized shipping rates (cents per ton-mile) are cotton several years after a single application. The 0.97 for barge, 2.53 for rail, and 5.35 for truck trans- result was a much greater cumulative profit where port. Most growers will be reluctant to pay more than gypsum was applied than where it was not used (Table $20–25 per ton for FGD gypsum delivered and spread 5-4). It must be noted that after the first year, the on their fields. economic return was actually negative. Also, correc- To reduce transportation costs, the FGD gypsum must tion of subsoil acidity or improved soil aeration and be dewatered. This can be done by simply placing the water infiltration are benefits that may not be immedi- FGD gypsum in piles and allowing gravity to leach the ately noticed. The benefits of gypsum must be substan- water out of the piles. A dedicated dewatering facility tial enough, over multiple years, to justify the cost of may also be used to reduce the water content in FGD application. The producer will then be more likely gypsum. Cost of constructing a dewatering facility convinced that the long-term benefits will eventually ranges from $3 to $6 million (Miller, 2006). Costs are repay the costs involved for purchase, transportation, about $3 per ton to operate a dewatering facility. Thus and spreading. it is doubtful that mechanical dewatering can be justified based solely on an agricultural market. At sites Table 5-4. Effect of Gypsum on Cotton Yield and where FGD gypsum must be mechanically dewatered Cumulative Profit in Georgia. (Sumner, 2007.) so that it can be hauled to a stacking area for disposal, the utility will not avoid the dewatering costs but Lint Cotton Yield (lbs/acre) could still provide gypsum for agriculture in the Treatment 2000 2001 2002 2003 2004 immediate area of where it is produced. Cost of Control 310 770 892 339 665 hauling varies but the rule of thumb for estimating trucking costs is $1 per ton to load a truck, $1 per ton Gypsum 309 989 1,117 384 774 for the first mile, and $0.10 per ton for each additional Difference –1 219 225 45 109 mile hauled. Value ($) 0 109 112 22 54 For end users, ordinary spreaders for application of Cumulative –50 59 171 193 247 fertilizers may be used for FGD gypsum application. profit ($) Many farm cooperatives or growers already have this equipment for fertilizer applications and do not need to purchase anything new for application of the FGD Some of the previous examples are for application of gypsum. The cost for a new spreader at the present mined gypsum, but FGD gypsum represents a new time (2010) can approach $100,000. Truck loading source that is increasingly becoming available. equipment, or some other means of loading, will also Research conducted to date shows that FGD gypsum be required. However, ordinary loading equipment is for agricultural uses performs similarly in comparison often a necessary tool on most farms so that purchase to other products that are routinely used for the same of a loader specifically to handle FGD gypsum would purposes. Thus, if the combined costs of purchasing, not be necessary. The spreading costs for FGD gypsum transport, and spreading are similar or lower for FGD would be similar to spreading costs for lime. gypsum, its use would seem to be warranted.

Gypsum as an Agricultural Amendment: General Use Guidelines 25 References Chen, L., Y. B. Lee, C. Ramsier, J. Bigham, B. Slater, Sumner, M. E. 2007. Soil chemical responses to FGD and W. A. Dick. 2005. Increased crop yield and gypsum and their impact on crop yields. Presented economic return and improved soil quality due to at the workshop on Agricultural and Industrial land application of FGD-gypsum. In: Proceeding of Uses of FGD Gypsum. October 2007 in Atlanta, the World of Coal Ash, April 11–15, 2005. Ga. http://library.acaa-usa.org/3-Soil_Chemical_ Lexington, Ky. Responses_to_FGD_Gypsym_and_Their_ Miller, E. C. 2006. Flue gas desulfurization (FGD) Impact_on_Crop_Yields.pdf. gypsum production, processing and disposal. Sumner, M. E. and L. Larrimore. 2006. Use of gypsum Presented at the workshop on Research and for crop production on southeastern soils. Demonstration of Agricultural Uses of Gypsum Presented at the workshop on Research and and Other FGD Materials. September 2006, St. Demonstration of Agricultural Uses of Gypsum Louis, Mo. http://www.oardc.ohio-state.edu/ and Other FGD Materials. September 2006, St. agriculturalfgdnetwork/workshop_files/ Louis, Mo. http://www.oardc.ohio-state.edu/ presentation/Session2/Miller%20-%20FGD%20 agriculturalfgdnetwork/workshop_files/ Gypsum%20Production,%20Processing,%20 presentation/Session1/Larrimore%20-%20 and%20Disposal.ppt. Gypsum%20for%20Crop%20Production%20 on%20Southeastern%20Soils.ppt.

26 Gypsum as an Agricultural Amendment: General Use Guidelines Analytical and Technical Support

Sampling and Analysis of FGD Gypsum container with information regarding the field and and Soil date. After packaging, soil samples may be sent to the STAR Laboratory (http://www.oardc.ohio-state.edu/ A. Sampling FGD Gypsum for Analysis starlab/) at the Ohio Agricultural Research and Devel- opment Center in Wooster, Ohio, or a commercial To make the most appropriate and environmentally laboratory of choice for chemical analysis. For more responsible use of new FGD gypsum sources, it is information about soil sampling and analysis, see the necessary to test the FGD gypsum to accurately deter- Ohio Agronomy Guide (Ohio State University Exten- mine the concentrations of its nutrients, calcium and sion, 1995). The use of this data for making gypsum sulfur. If there is concern about its environmental rate recommendations is provided in Chapter 4. impact, concentrations of other elements such as arsenic, cadmium, lead, mercury, and selenium should Table 6-1. Chemical Characteristics of FGD Gypsum also be measured. For the test results to be mean- from Five States. (FGD Gypsum Agricultural Network, ingful, it is important to obtain an adequate number of 2008.) samples that are representative of the stockpile of FGD State State State State State gypsum. The number of samples needed depends on Parameter the variability of FGD gypsum. The more variable the 1 2 3 4 5 FGD gypsum, the more samples are required. FGD pH 7.7 8.4 8.0 7.7 7.7 gypsum from different storage systems should be EC† (dS/m) 1.8 3.8 2.0 1.9 2.0 sampled separately. The composition and concentra- † tions of elements of environmental concern in FGD TNP (%) 10 < 5.0 13 21 3.2 Calcium gypsum depend on the type of coal, scrubbing process, 203 202 192 200 88 and sorbent used in the desulfurization process. (mg/g) Sulfur FGD gypsum subsamples should be collected from at 157 174 178 183 184 least three representative locations in stockpiled (mg/g) gypsum and at least 20 inches below the surface. At † EC is electrical conductivity and TNP is total neutralization potential. each spot, a minimum of one pound of FGD gypsum should be collected and put in a plastic bag. Total weight of the sample will be about 3–5 pounds. Iden- tify the sample container with information regarding Institutional Support its source and a date. After packaging, FGD gypsum samples may be sent to the STAR Laboratory (http:// Ohio State University Extension www.oardc.ohio-state.edu/starlab/) at the Ohio Agri- The primary objective of The Ohio State University cultural Research and Development Center in and Ohio State University Extension (OSU Extension) Wooster, Ohio, for chemical analysis. is to provide Ohio’s citizens with objective research- FGD samples from five power plants in Alabama, based information (http://www.extension.osu.edu). Arkansas, Indiana, North Dakota, and Ohio were OSU Extension provides a wide range of research- collected and sent to the Ohio Agricultural Research based educational programs and publications. Infor- and Development Center for relevant agronomic anal- mation is available through professional Extension ysis. The results are provided in Table 6-1. It is evident educators in each county and through state special- that FGD gypsum is an excellent source of calcium ists. Publications such as fact sheets and bulletins can and sulfur for supporting crop growth. also be downloaded from the Ohioline website (http://ohioline.osu.edu/). The Ohioline website is B. Sampling Soil for Analysis maintained by the College of Food, Agricultural, and Environmental Sciences of The Ohio State University. To obtain a representative soil sample, subsamples This site is used extensively by the citizens of Ohio to must be collected from at least three spots in each obtain credible information related to agricultural uniform field area from the surface to 20 cm depth. and environmental issues. An Extension fact sheet Approximately one-half pound of soil at each spot is entitled Gypsum for Agricultural Use in Ohio—Sources collected and put in a plastic bag. Total weight of a and Quality of Available Products can be downloaded sample is about two pounds. Identify the sample from the Ohioline site.

Gypsum as an Agricultural Amendment: General Use Guidelines 27 National Research and Demonstration Network of ments for its use with the appropriate state’s environ- FGD Products in Agriculture mental agency. A complementary project to this one is the National The principal federal law that regulates hazardous and Research and Demonstration Network of FGD Prod- solid wastes is the Resource Conservation and ucts in Agriculture (http://www.oardc.ohio-state.edu/ Recovery Act (RCRA). Subtitle C of RCRA regulates agriculturalfgdnetwork/). Research has been wastes that are both “solid” and “hazardous.” Wastes completed or is currently being conducted in that are not considered hazardous are regulated under Alabama, Arkansas, Indiana, New Mexico, North Subtitle D, which passes landfill permitting and moni- Dakota, Ohio, and Wisconsin. toring responsibilities to the states. In 1980, RCRA was Members of the national network have organized three amended by adding what is known as the Bevill exclu- workshops about land application uses of FGD prod- sion, to exclude “solid waste from the extraction, ucts. These workshops were held in St. Louis (2006), benefication, and processing of ores and minerals” Atlanta (2007), and Indianapolis (2009). Papers from regulation as hazardous waste under Subtitle C presented in the workshops can be accessed at the of RCRA. This exclusion holds until a determination is FGD Network website (http://www.oardc.ohio-state. made by the EPA Administrator either to promulgate edu/agriculturalfgdnetwork/). regulations under Subtitle C or to declare such regulations unwarranted. American Coal Ash Association (ACAA) As required by Congress, the U.S. Environmental The mission of the American Coal Ash Association Protection Agency (U.S. EPA) published regulatory (ACAA) is to advance the management and use of coal determinations in 1993 for fly ash, bottom ash, boiler combustion products in ways that are environmentally slag, and FGD materials and in 2000 for fluidized bed responsible, technically sound, commercially competi- combustion wastes, co-managed wastes, and wastes tive, and more supportive of a sustainable global from coal combustion by non-utilities, petroleum coke community. The association accomplishes its mission combustion, co-burning of coal and fuel, and oil and through public-private partnerships, technical assis- natural gas combustion. These determinations tance, education, publications, meetings, workshops, concluded that regulation of CCPs under Subtitle C and other activities and initiatives. The ACAA facili- was not warranted and that federal regulation of bene- tates connections among members as well as diverse ficial use was not necessary. However, it was concluded entities and interests to stimulate proper use of that national regulations for disposal in landfills and gypsum. Additional information can be obtained at surface impoundments under Subtitle D should be http://acaa.affiniscape.com/index.cfm. developed. In addition, the EPA indicated it would continue to review information related to coal Soil and Crop Consultants combustion by-products. Soil and crop consultants are qualified individuals As a result of the regulatory determination made in who offer planning and technical assistance to agricul- 1993 and 2000, states have developed their own regula- tural producers and make natural resource manage- tory systems for CCBs. All states except California, ment decisions. Producers are not required to use Washington, Rhode Island, and Tennessee designate private consultants, but they have this option for help FGD materials as exempt from regulation as with FGD gypsum management. Several soil and crop hazardous wastes (Table 6-2). Those four states treat consultants have experience working with FGD FGD materials like all other industrial wastes and gypsum uses in agriculture. You may find more infor- require FGD material to be tested to determine if they mation by conducting a web search using the search contain constituents at levels used to define hazardous terms of “FGD gypsum” and “agriculture.” wastes. If these levels are exceeded, the material is treated as a hazardous waste. If not, the materials are treated as a non-hazardous waste. Most states regulate Rules and Regulations FGD materials as solid wastes and some categorize it Rules and regulations concerning FGD gypsum use in more narrowly as industrial solid wastes, or special agriculture and information about those rules are wastes. New Jersey, Oklahoma, and Utah exempt coal constantly being revised. It is important to verify the combustion by-products as solid wastes under certain regulatory status of FGD gypsum and any require- uses or conditions.

28 Gypsum as an Agricultural Amendment: General Use Guidelines Table 6-2. State Regulations for FGD Gypsum. States that currently have laws authorizing land- application uses are Illinois, Maryland, Michigan, Regulation State Missouri, Nebraska, North Carolina, Pennsylvania, Chemical analysis before California, Rhode Island, Virginia, and West Virginia. The specific language being exempted as Tennessee, Washington describing reuse varies by state but is generally hazardous waste defined for materials being used as a soil substitute, Land application as solid Illinois, Maryland, additive or nutrient additive, conditioner, or amend- waste Michigan, Missouri, ment. Illinois, Maryland, Pennsylvania, and Virginia Nebraska, North Carolina, include mine reclamation as a reuse. Virginia appears Pennsylvania, Virginia, to have one of the broadest definitions for reuse as a West Virginia soil nutrient or other agricultural use. Maryland No law or as solid waste Alabama, Alaska, Arizona, includes reuse as a soil improver or conditioner. case-by-case Arkansas, Colorado, Connecticut, Delaware, Thirty-two states do not have laws or permit-by-rule Georgia, Hawaii, Idaho, arrangements specifically authorizing reuse of FGD Indiana, Iowa, Kansas, materials. Several states (Indiana, New York, Texas, Kentucky, Louisiana, Utah, and Wisconsin) that have laws authorizing reuse Maine, Massachusetts, of FGD materials generally specify construction (road Minnesota, Mississippi, building) or other engineering uses instead of land- Missouri, Montana, application uses. Fifteen states evaluate proposals for Nevada, New Hampshire, reuse on a case-by-case basis. Ohio and Oklahoma lack New Jersey, New Mexico, specific laws for reuse but do permit land application New York, North Dakota, under other administrative arrangements. Ohio, Oklahoma, Oregon, South Carolina, South Dakota, Texas, Utah, References Vermont, Wisconsin, Ohio State University Extension. 1995. Ohio Agronomy Wyoming Guide. Bulletin 472. Ohio State University Exten- sion, Columbus, Ohio. Flue Gas Desulfurization Gypsum Agricultural Network. 2008. Progress Report—1015777. EPRI, Palo Alto, Calif.

Gypsum as an Agricultural Amendment: General Use Guidelines 29 Gypsum Handling and Storage

In this chapter, we briefly provide information about gypsum handling and storage, with special attention paid to FGD gypsum.

Handling and Transportation Gypsum, including FGD gypsum, is not combustible Figure 7-2. Trucks (left), rail cars (middle), and river barges or explosive. FGD gypsum is also not expected to pro- (right) are used for FGD gypsum transportation. (From duce any unusual hazards during normal use. Under FGD Network website: http://www.oardc.ohio-state.edu/ ordinary conditions, no glasses or goggles, gloves and agriculturalfgdnetwork.) protecting clothing, and respiratory protection are required for handling of FGD gypsum. However, exposure to high dust levels may irritate the skin, eyes, The issue of transportation costs understandably arises nose, throat, or upper respiratory tract. Therefore, as whenever potentially large volume uses of FGD much as possible, minimize dust generation and accu- gypsum are proposed. Comparative generalized ship- mulation and avoid breathing FGD gypsum dust. In ping rates (cents per ton-mile) are lowest for barge, storage areas, provide ventilation sufficient to control intermediate for rail, and highest for truck transport. airborne dust levels. If dust is being generated, wear Some rules of thumb that pertain to FGD transport is the appropriate eye protection, such as safety glasses or that it can be transported up to 551 miles by barge, 211 goggles, and a dust respirator (Figure 7-1). miles by rail, but only 100 miles by truck before the shipping costs exceed its value. If the source and markets for the material are near a navigable waterway or rail line, and assuming a 100-mile radius is the truck transportation limit, material storage sites located at 200-mile intervals along a rail line or barge route could be set up for moving the FGD gypsum from the utility to the farmer.

Gypsum Storage FGD gypsum may be stored in the open or in a Figure 7-1. Goggles and mask for eye and respiratory covered structure (Figure 7-3). FGD gypsum storage protection. should accomplish the following goals: (1) Minimize water interaction; (2) reduce dust; (3) balance capital investment, cash flow requirements, and labor costs, FGD gypsum can build up or adhere to the walls of a and (4) maintain good physical condition of the FGD confined space, and the FGD gypsum can release, gypsum for spreading. FGD gypsum storage is needed collapse, or fall unexpectedly. To prevent burial or to provide handling and spreading flexibility. suffocation, do not enter a confined space, such as a Spreading is often seasonal and needs to be scheduled silo, bin, bulk truck, or other storage container or to avoid wet ground, poor weather conditions, growing vessel that stores or contains FGD gypsum. crops, and conditions conducive to causing pollution. FGD gypsum is not classified or regulated. It is not like Storage areas or facilities should be constructed to hazardous materials that require Department of minimize any potential dust, surface water runoff Transportation shipping permission and documenta- problems, and access by animals through proper tion for transportation. Depending on the distance fencing. Although higher in cost, a covered structure from the FGD gypsum source to locations where FGD may be practical due to improved handling conditions, gypsum is used, trucks, rail cars, and river barges may less or no surface water runoff, and less spreading of be used for FGD gypsum transportation (Figure 7-2). dust. Dewatered gypsum stored in a roofed storage Currently, the most common way to transport FGD shed without side walls may need a wind screen to gypsum is by truck. prevent dusting. FGD gypsum stored outside will

30 Gypsum as an Agricultural Amendment: General Use Guidelines generally form a crust that helps shed water and Water runoff from FGD gypsum stockpiles, whether prevents dusting so long as it is undisturbed. If the from rainfall or snowmelt, may contain unaltered crust is broken, a dusting problem may result. FGD gypsum and soil. If gypsum is stockpiled in an individual field for post-harvest application and then completely spread before winter, no action is needed other than that of constructing a temporary storage pile. If gypsum is stored in large piles in an open-lot system, a management plan should be developed to avoid dust and water problems from developing and to restrict cattle access. Runoff can be collected and Figure 7-3. Gypsum stockpiled in the field for post-harvest transferred to a settling basin or holding pond by application (left), in the coal-fired power plant for marketing constructing diversion, curbs, gutters, lot paving, and, (middle), and in the covered structure (right). (From the FGD in some cases, by pumping (Figure 7-4). A settling Network website: http://www.oardc.ohio-state.edu/ basin or a holding pond retains runoff and reduces the agriculturalfgdnetwork.) flow rate to allow settling out and recovery of FGD gypsum. Typically, any runoff FGD gypsum that will settle out will do so in about 30 minutes. To prevent When planning the construction of FGD gypsum scouring of the settled FGD gypsum from the settling storage facilities, things to consider include building basin, the liquid cross-sectional area that enters the locations, well locations, future building expansions, pond should be about 5% of the ponded surface area. and prevailing winds. The storage facility will also After settling, the liquids can be drained off to a need to be properly sized for convenient filling and constructed wetland or vegetative treatment area, used emptying. As much as possible, all-weather access for irrigation, or discharged to a surface water body. should be provided. Both open and in facility FGD gypsum storage systems have advantages and disadvantages. A detailed comparison is provided in Table 7-1.

Table 7-1. Comparison of FGD Gypsum Storage Alternatives.

FGD Storage Advantages Disadvantages Type Open (not Inexpensive. Rainfall adds covered) extra water. Rainfall/runoff contamination potential. Figure 7-4. Components of a runoff control system. Runoff controls may be required. Open (covered Less expensive. Not feasible When FGD gypsum is stored, dust control is impor- with plastics) No rainfall effects. for long-term storage. tant. Moisture content and weather conditions signif- Maintains FGD icantly affect dust generation and transportation. gypsum moisture. Dust is generated from FGD gypsum storage and Open sided No rainfall effects. Expensive. handling systems. FGD gypsum that has moisture (roof cover Maintains FGD content as low as 5% will not cause dust problems only) gypsum moisture. while loading. However, dry FGD gypsum that has In facility No rainfall effects. Most expensive. moisture content less than 5% will dust while being spread using a spinner spreader, especially on windy Feasible for long- term storage. days (Figure 7-5). Application can also be done using a drop box spreader, which helps control potential Maintains FGD dusting problems. gypsum moisture.

Gypsum as an Agricultural Amendment: General Use Guidelines 31 References Curtis, K. 2007. Marketing of FGD gypsum in the Midwest United States. Presented at the workshop on Agricultural and Industrial Uses of FGD Gypsum. October 2007 in Atlanta, Ga. http:// library.acaa-usa.org/2-Marketing_of_FGD_ Gypsum_in_the_Midwest_US.pdf. Miller, E. C. 2007. What is FGD gypsum? Presented at the workshop on Agricultural and Industrial Uses of FGD Gypsum. October 2007 in Atlanta, Ga. http://library.acaa-usa.org/2-what_is_FGD_ Gypsum.pdf.

Figure 7-5. Application on dry windy days may generate dust. (Curtis, 2007.)

For FGD gypsum producers, using covered conveyors at transfer points is one of the best ways for dust control when distributing FGD gypsum to marketers or end users (Figure 7-6). However, this method is not necessary for most users to transfer their FGD gypsum to fields from the stockpile because of great capital investment and the difficulty of installation. Often, FGD gypsum that is stored uncovered outside will form a crust and prevent dusting. Treating FGD gypsum stockpiles by spraying water can also prevent dusting.

Figure 7-6. A covered conveyor distributes FGD gypsum at transfer points. (Miller, 2007.)

32 Gypsum as an Agricultural Amendment: General Use Guidelines List of Figures Page Flue gas desulfurization (FGD) product is created by a scrubber that removes sulfur dioxide (SO ) Figure 1-1 2 5 from the flue gas stream when energy sources containing high concentrations of sulfur are burned. Increase of total coal combustion products (CCPs) including fly ash (FA), bottom ash (BA), boiler Figure 1-2 5 slag (BS), and flue gas desulfurization (FGD) materials from 1966 to 2006. Figure 1-3 Schematic of the scrubbing process to produce FGD gypsum. 6 Figure 2-1 Decline of total sulfur deposition in north central Ohio (Wooster, Ohio) from 1979 to 2008. 8 Gypsum as a sulfur fertilizer to enhance alfalfa production. Gypsum was an early form of fertilizer Figure 2-2 8 used in the United States and is an excellent source of calcium and sulfur. Figure 2-3 Gypsum as a calcium fertilizer to enhance peanut production. 9 Gypsum as a soil amendment to improve soil physical properties. Addition of soluble Ca can Figure 2-4 overcome the dispersion effects of Mg or Na ions and help promote flocculation and structure 9 development in dispersed soils. Infiltration rate for a Blount soil with and without surface-applied gypsum. Gypsum can serve as a Figure 2-5 9 soil amendment to improve soil physical properties and water infiltration and percolation. Dispersion of soil particles and then surface drying creates a crust that impedes seedling Figure 2-6 emergence. Gypsum as a soil amendment can improve soil physical properties to prevent 10 dispersion and surface crust formation. Figure 2-7 Effects of aluminum (Al3+) on growth of fescue. 10 Figure 2-8 Calcium and sulfur movement into soil profiles is enhanced by the addition of gypsum. 10 Soluble aluminum (Al3+) is toxic to plants. Gypsum can react with Al3+, thus removing it from the soil Figure 2-9 11 solution and greatly reducing its toxic effects. Gypsum as a soil amendment to remediate subsoil acidity. Calcium and sulfur movement into soil Figure 2-10 11 profiles is enhanced by the addition of gypsum. Soluble aluminum (Al3+) is toxic to plants. Gypsum can react with Al3+, thus removing it from soil Figure 2-11 solution and greatly reducing its toxic effects. Subsoil acidity due to Al3+ can be overcome by 11 gypsum additions, thus promoting deeper rooting of plants. Yields of alfalfa at Wooster, Ohio, (cumulative yields for years 2000–2002) were increased by the Figure 3-1 13 addition of gypsum, which improves the sulfur nutritional status of the soil. Figure 3-2 Application of FGD gypsum increases water infiltration and percolation. 14 Figure 3-3 Effect of gypsum on runoff phosphorus. 14 Figure 3-4 Gypsum as a soil amendment to remediate sodic or sodium-affected soils. 15 Figure 3-5 FGD gypsum as a component of synthetic soils for nursery and greenhouse use. 15 Figure 3-6 FGD gypsum being applied to the soil surface of a golf course. 16 Figure 4-1 FGD gypsum can be applied directly to the soil surface using conventional dry material spreaders. 21 Figure 5-1 Income response for application of FGD gypsum for peanut in the southeastern United States. 24 Figure 7-1 Goggles and mask for eye and respiratory protection. 30 Figure 7-2 Trucks, rail cars, and river barges are used for FGD gypsum transportation. 30 Gypsum stockpiled in the field for post-harvest application, in the coal-fired power plant for Figure 7-3 31 marketing, and in the covered structure. Figure 7-4 Components of a runoff control system. 31 Figure 7-5 Application on dry windy days may generate dust. 32 Figure 7-6 A covered conveyor distributes FGD gypsum at transfer points. 32

Gypsum as an Agricultural Amendment: General Use Guidelines 33 List of Tables Page Table 1-1 FGD Gypsum Production, Total Use, and Agriculture Use from 2003 to 2008 in the United States. 6 Some Mineralogical and Physical Properties of FGD Gypsum from the W. H. Zimmer Station of Duke Table 1-2 6 Energy (Moscow, Ohio) and Mined Gypsum from the Kwest Group (Port Clinton, Ohio). Chemical Properties of FGD Gypsum from the W. H. Zimmer Station of Duke Energy (Moscow, Ohio) Table 1-3 7 and Mined Gypsum from the Kwest Group (Port Clinton, Ohio). Effects of Nitrogen and Sulfur (S) Fertilizers on Corn Yields Grown in Wooster Silt Loam from 2002 to Table 3-1 13 2005. Table 3-2 Effect of FGD Gypsum on the Yield, Value, and Calcium (Ca) Content of Peanuts Grown in Florida. 14 Table 3-3 Effect of FGD Gypsum on the Yield of Cotton in an Acid Subsoil in Mississippi. 15 Harvest Removal of Sulfur (S) by Various Crops at Specific Yields and the Amount of Gypsum Needed Table 4-1 18 to Replace the Removed Sulfur. Table 4-2 Critical Sulfur Concentrations in Crop Plants. 19 The Amount of Gypsum Application Needed to Supply Specific Amounts of Sulfur Nutrient to Table 4-3 Support the Growth of Various Crops. These Suggestions Are Broadly Based on the Amount of Sulfur 20 Removed at Harvest and Lost Due to Leaching. Application Rates of Sulfur (S) and Calcium (Ca) Calculated Based on the Amount of Gypsum Table 4-4 20 Application. Equations to Estimate the Gypsum Requirement (GR) for Remediating Subsoil Acidity, Magnesium Table 4-5 21 Soils, and Sodic Soils. Table 4-6 Rate, Time, and Method of Application of Gypsum for Various Functions. 22 Total Costs and Return Above Total Costs for Two Different Management Systems (NT—no tillage Table 5-1 24 and CT—conventional tillage) for Corn and Soybean Production. Table 5-2 Effect of FGD Gypsum on Peanut Yields and Value in Florida, Mississippi, Georgia, and Alabama. 24 Table 5-3 Effect of Gypsum on Tomato Yield and Value in Mississippi. 25 Table 5-4 Effect of Gypsum on Cotton Yield and Cumulative Profit in Georgia. 25 Table 6-1 Chemical Characteristics of FGD Gypsum from Five States. 27 Table 6-2 State Regulations for FGD Gypsum. 29 Table 7-1 Comparison of FGD Gypsum Storage Alternatives. 31

Abbreviations and Basic Element Symbols Conversion Factors Element Symbol Element Symbol Element Symbol CCP — Coal combustion product Aluminum Al Copper Cu Phosphorus P CEC — Cation exchange capacity Antimony Sb Iron Fe Potassium K EC — Electrical conductivity Arsenic As Lead Pb Sodium Na FGD — Flue gas desulfurization Barium Ba Lithium Li Sulfur S GR — Gypsum requirement Beryllium Be Magnesium Mg Selenium Se TNP — Total neutralization potential Boron B Manganese Mn Silicon Si ppm (parts per million) — mg/kg Cadmium Cd Mercury Hg Strontium Sr ppb (parts per billion) — µg/kg Calcium Ca Molybdenum Mo Thallium Tl Chromium Cr Nickel Ni Vanadium V ppt (parts per trillion) — ng/kg Cobalt Co Nitrogen N Zinc Zn

34 Gypsum as an Agricultural Amendment: General Use Guidelines Conversion Factors for SI and Non-SI units To convert Column 1 into Column 1 Column 2 To convert Column 2 into Column 2, multiply by SI Unit Non-SI Unit Column 1, multiply by Area 2.47 Hectare, ha Acre 0.405 247 Square kilometer, km2 (106 m2) Acre 4.05 x 10-3 0.386 Square kilometer, km2 (106 m2) Square mile, mi2 2.590 2.47 x 10-4 Square meter, m2 Acre 4.05 x 103 10.76 Square meter, m2 Square foot, ft2 0.0929 1.55 x 10-3 Square millimeter, mm2 (10-6 m2) Square inch, in2 645 Volume 9.73 x 10-3 Cubic meter, m3 Acre-inch 102.8 35.3 Cubic meter, m3 Cubic foot, ft3 0.0283 6.10 x 104 Cubic meter, m3 Cubic inch, in3 1.64 x 10-5 0.0284 Liter, L (10-3 m3) Bushel, bu 35.24 1.057 Liter, L (10-3 m3) Quart (liquid), qt 0.946 0.0353 Liter, L (10-3 m3) Cubic foot, ft3 28.3 0.265 Liter, L (10-3 m3) Gallon 3.78 33.78 Liter, L (10-3 m3) Ounce (fluid), oz 0.0296 2.11 Liter, L (10-3 m3) Pint (fluid), pt 0.473 Mass 2.20 x 10-3 Gram, g (10-3 kg) Pound, lb 454 0.0352 Gram, g (10-3 kg) Ounce, oz 28.4 2.205 Kilogram, kg Pound, lb 0.454 0.01 Kilogram, kg Quintal (metric), q 100 1.10 x 10-3 Kilogram, kg Ton (2000 lb), ton 907 1.102 Megagram, Mg (tonne) Ton (U.S.), ton 0.907 1.102 Tonne, t Ton (U.S.), ton 0.907 Yield and Rate 0.893 Kilogram per hectare, kg ha-1 Pound per acre, lb acre-1 1.12 0.0777 Kilogram per cubic meter, kg m-3 Pound per bushel, lb bu-1 12.87 0.0149 Kilogram per hectare, kg ha-1 Bushel per acre, 60 lb 67.19 0.0159 Kilogram per hectare, kg ha-1 Bushel per acre, 56 lb 62.71 0.0186 Kilogram per hectare, kg ha-1 Bushel per acre, 48 lb 53.75 0.107 Liter per hectare, L ha-1 Gallon per acre 9.35 893 Tonnes per hectare, t ha-1 Pound per acre, lb acre-1 1.12 x 10-3 893 Megagram per hectare, Mg ha-1 Pound per acre, lb acre-1 1.12 x 10-3 0.446 Megagram per hectare, Mg ha-1 Ton (2,000 lb) per acre, ton acre 2.24

Gypsum as an Agricultural Amendment: General Use Guidelines 35